Advanced Wind Turbine Program Next Generation Turbine ... - NREL

Contents
List of Tables ............................................................................................................................... vii
1 Introduction and Project Overview ........................................................................................... 1
1.1 Project Background ........................................................................................................... 1
1.2 Scope of Work.................................................................................................................. 1
2 Concept Studies ......................................................................................................................... 3
2.1 Electromechanical Systems Concepts ............................................................................... 4
2.1.1 Conventional-Speed Generators and Multi-stage Gearboxes ................................ 8
2.1.1.1 Alternative Converter Topologies. ........................................................... 8
2.1.1.2 High-Speed, Variable-Speed Operation of Alternative Generators ......... 9
2.1.1.3 Fixed-Speed Operation of Conventional Generators ............................. 10
2.1.1.4 Multiple Conventional-Speed Generators .............................................. 11
2.1.2 Medium-Speed Generators and Single-Stage Gearboxes .................................... 12
2.1.2.1 Medium-Speed Wound Rotor Induction Generator ............................... 12
2.1.2.2 Medium-Speed Squirrel Cage and Synchronous Generators ................. 13
2.1.2.3 Multiple Medium-Speed Generators ...................................................... 14
2.1.3 Direct-Drive Generators ....................................................................................... 14
2.1.3.1 Fixed-Speed Direct-Drive Machines...................................................... 15
2.1.3.2 Variable Speed Direct-Drive Machines ................................................. 15
2.1.3.3 Tubular Nacelle (External Monocoque)................................................. 16
2.1.4 Summary of Drive Train Concepts ...................................................................... 18
2.2 Controls Concepts ........................................................................................................... 19
2.3 Rotor and Structural Design Concepts ............................................................................ 20
2.3.1 Rotor and Structural Flexibility............................................................................ 21
2.3.1.1 Upwind Rotor Blade and Tower Flexibility........................................... 22
2.3.1.2 Machine Carrier Yaw and Nodding Compliance ................................... 25
2.3.1.3 Flexible Downwind Rotor Concepts ...................................................... 29
2.3.2 Concurrent Aerodynamic and Structural Design Optimization ........................... 31
2.3.3 Aeroelastic Tailoring of Rotor Blades ................................................................. 33
2.3.4 Cast Blade Roots .................................................................................................. 35
2.3.5 Boundary Layer Control....................................................................................... 38
2.4 Variable Diameter Rotor ................................................................................................. 38
2.5 Summary of Concept studies........................................................................................... 40
3 Proof of Concepts Turbine ...................................................................................................... 41
3.1 Design of the POC1.5/70.5.............................................................................................. 41
3.1.1 Tower and Foundation Design ............................................................................. 45
3.1.2 Drive Train Design and Testing ........................................................................... 45
3.1.3 Controls System Design ....................................................................................... 46
3.1.4 POC 34-m Rotor Blade Design and Testing ........................................................ 49
3.1.5 POC Hub Analysis ............................................................................................... 56
3.2 Installation and Testing of the Proof of Concepts Turbine ............................................. 56
3.2.1 Power Performance Testing of the POC Turbine................................................. 58
3.2.2 Power Quality Testing of the POC Turbine ......................................................... 58
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